Tropical Agriculture Research Front

Ishigaki, Japan

Tropical Agriculture Research Front

Ishigaki, Japan
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Kobori Y.,Tropical Agriculture Research Front | Nakata T.,Tropical Agriculture Research Front | Ohto Y.,Tropical Agriculture Research Front | Takasu F.,Nara Women's University
Applied Entomology and Zoology | Year: 2010

Artificial release of marked adult Diaphorina citri, the insect vector of citrus greening disease, was performed in July 2007 (10,000 adults released, experiment 1) and October 2008 (1,000 adults released, experiment 2) to determine the association of the dispersal pattern with disease invasion risk. During the experimental periods, in experiment 1, the mean dispersal distances from the release point were 5-6 m and in experiment 2 they were 6-12 m. Further examination of the relationship between dispersal distance and season is needed. The number of released D. citri declined with increasing distance from the release point and did not change markedly with time. The center of distribution moved little during the experimental period. These results suggest that the adult D. citri barely moved once they had colonized a host plant within a few days after their release. Our results also suggest that the released D. citri moved with the wind. The diffusion coefficient was estimated at 7.23 from experiment 1, but random diffusion might be a poor descriptor of the dispersal of adult D. citri. © The Japanese Society of Applied Entomology and Zoology 2010.

PubMed | Okinawa Prefectural Agricultural Research Center, Japan National Agriculture and Food Research Organization and Tropical Agriculture Research Front
Type: Journal Article | Journal: Breeding science | Year: 2016

Tropical fruit crops are predominantly produced in tropical and subtropical developing countries, but some are now grown in southern Japan. Pineapple (Ananas comosus), mango (Mangifera indica) and papaya (Carica papaya) are major tropical fruits cultivated in Japan. Modern, well-organized breeding systems have not yet been developed for most tropical fruit species. Most parts of Japan are in the temperate climate zone, but some southern areas such as the Ryukyu Islands, which stretch from Kyushu to Taiwan, are at the northern limits for tropical fruit production without artificial heating. In this review, we describe the current status of tropical fruit breeding, genetics, genomics, and biotechnology of three main tropical fruits (pineapple, mango, and papaya) that are cultivated and consumed in Japan. More than ten new elite cultivars of pineapple have been released with improved fruit quality and suitability for consumption as fresh fruit. New challenges and perspectives for obtaining high fruit quality are discussed in the context of breeding programs for pineapple.

Ohara S.,Asahi Group Holdings Ltd. | Fukushima Y.,National Cheng Kung University | Sugimoto A.,Tropical Agriculture Research Front | Terajima Y.,Tropical Agriculture Research Front | And 2 more authors.
Biomass and Bioenergy | Year: 2012

High yield sugarcane is expected to resolve the competition between food and fuel regarding farmland and biomass resources. However, its higher composition of reducing sugars (i.e., glucose and fructose), which inhibit sucrose crystallization, hinders the production of sugar from high yield sugarcane. Under the conventional integrated sugar-ethanol manufacturing system, high biomass yield causes only the increase of ethanol production because of the increase in unrecovered sugar after extraction, which represents a failure in resolving the competition. The technology presented here is the world's first to solve this problem via selective ethanol fermentation using Saccharomyces dairenensis, an unconventional yeast that ferments only reducing sugars and leaves sucrose untouched. A laboratory-scale test using sugarcane juices with a high composition of reducing sugars (100 g kg-1) resulted in a sucrose crystal yield increase from a single extraction, from 16.2 to 65.1%, by introducing selective fermentation. The second extraction, from the molasses, which was enabled by the lowered residual reducing sugar composition, further enhanced the total sugar crystal yield (up to 83.4%). A simulation of the application of this technology in the U.S.A. revealed that both sugar and ethanol production were enhanced, whereas sugar production declined by the mere adoption of high yield cultivar, even with the increase in sugarcane yield. © 2012 Elsevier Ltd.

Ichinose K.,Tropical Agriculture Research Front | Hoa N.V.,Southern Research Institute | Bang D.V.,Southern Research Institute | Tuan D.H.,Southern Research Institute | Dien L.Q.,Southern Research Institute
Crop Protection | Year: 2012

No sustainable management practices have been established yet for citrus greening disease (CG). Here we show the efficacy of interplanting guava on CG and its limitation. In 2004, four farmers in southern Vietnam found fewer occurrences of CG in their orchards with guava interplanting than in other orchards without it. The efficacy of guava interplanting was evaluated from field assessment in 93 citrus orchards in southern Vietnam. The CG infection was lowest in orchards where either chemical control with both non-neonicotinoid insecticides and neonicotinoids or the interplanting with guava was performed. Three field experiments were then carried out investigating guava interplanting. In these experiments, no citrus trees in orchards interplanted with guavas were infected by CG for over one year and a few months, while about 20% of trees were infected during the same period in orchards without guavas. There were significantly fewer psyllids in guava interplanted orchards in the first year, but the insect increased thereafter. Almost all trees were infected by CG after two and a half years irrespective of the presence of guavas, indicating that guava interplanting was effective for one year at most. Guava interplanting reduced invasion by the vector but failed to regulate its subsequent generation succession. © 2011 Elsevier Ltd.

Kobori Y.,Tropical Agriculture Research Front | Okabe K.,Japan Forestry and Forest Products Research Institute | Kanzaki N.,Japan Forestry and Forest Products Research Institute
Nematology | Year: 2015

An undescribed Bursaphelenchus species was isolated and cultured from Dorcus titanus sakishimanus collected during a field survey of the insect-Associated nematodes in subtropical Japan. The stag beetles were collected from Ishigaki Island, Okinawa, Japan, and dissected to examine their nematode associates. Then the dissected bodies were individually transferred to 2.0% agar plates, and nematode propagation on the plates was periodically examined. Nematodes were first recovered from the agar plate, i.e., the number of nematodes carried by the beetle was low, and infection was not confirmed during dissection. The new species was morphologically and phylogenetically (on a molecular basis) close to B. gerberae, which was isolated from the palm weevil, Rhynchophorus palmarum (Curculionidae), from tropical America, and to other weevil-Associated Bursaphelenchus species. However, the new species can be distinguished from its close relatives by its typological characters, e.g., long and slender female tail and male spicule morphology as well as phylogenetic status inferred from the near-full-length of the small subunit (SSU) of the ribosomal RNA gene. The new species is described and illustrated herein as B. sakishimanus n. sp. and its molecular profiles, near-full-length SSU, and D2-D3 expansion segments of the large subunit of ribosomal RNA are described. This is the second Bursaphelenchus species associated with stag beetles (Lucanidae). © 2015 Koninklijke Brill NV, Leiden.

Montoya-Alvarez A.F.,Kochi University | Ito K.,Kochi University | Ito K.,Japan Science and Technology Agency | Nakahira K.,Kochi University | And 2 more authors.
Applied Entomology and Zoology | Year: 2010

The functional response of the indigenous green lacewing Chrysoperla nipponensis (Okamoto) and the imported green lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae) feeding on seven different densities of the cotton aphid Aphis gossypii (Glover) (Homoptera: Aphididae) was studied under laboratory conditions at 20°C. C. nipponensis and C. carnea have shown a Type II functional response based on logistic regression analysis. The maximum number of prey eaten by C. carnea was higher than C. nipponensis. Handling time decreased at 24 h for both species, but was higher for C. nipponensis at 12 and 24 h than for C. carnea. The attack coefficient of C. nipponensis was slightly higher than C. carnea in second and third instars. These results indicate that C. carnea may eat more aphids at high prey densities; however, C. nipponensis could be considered a prospective candidate for use as a commercial biological control agent for aphids in Japan. C. nipponensis will become more important than C. carnea from the viewpoint of environmental safety because it is a native species adapted to the Japanese environment, and nontarget effects can be avoided.

Ishizaki T.,Japan International Research Center for Agricultural science | Ishizaki T.,Tropical Agriculture Research Front | Kumashiro T.,Japan International Research Center for Agricultural science
In Vitro Cellular and Developmental Biology - Plant | Year: 2011

In the use of genetic transformation in breeding, there are several possible problems including multiple copy insertion of transgene, sterility caused by somaclonal variation and gene silencing. In this study, we characterized transgenic New Rice for Africa (NERICA) produced by Agrobacterium-mediated methods with respect to copy number of transgene, fertility, and expression level of an introduced GUS gene. Southern blot analysis of primary transformants demonstrated that about half of the events carried a single copy of the transgene regardless of the cell density of Agrobacerium for inoculation. We examined ten procedures, consisting of different time periods and times of subculture for callus formation and the starting times of hygromycin-based selection of transformed cells, for transformation of NERICA cultivars to produce transformants within a short culture period at high frequency. A new culture method developed in this study required only about 1.5 mo from the beginning of tissue culture to transformants, whereas a standard protocol we developed previously needed about 2 mo of culture; however, it did not significantly reduce percentages of sterile plants. Fertile T0 plants produced fertile T1 plants at higher frequency. However, fertility was not inherited in a simple fashion: both fertile and partially sterile T0 plants produced fertile, partially sterile and sterile T1 plants. Expression assay of an introduced GUS gene revealed position effects in seven independent homozygous transformed lines carrying one copy of the transgene. Points to pay attention to in the use of genetic transformation in breeding are discussed. © 2011 The Society for In Vitro Biology.

Takano S.-I.,Kyushu University | Takasu K.,Kyushu University | Fushimi T.,Tropical Agriculture Research Front | Ichiki R.T.,Kyushu University | And 2 more authors.
Entomological Science | Year: 2012

The coconut hispine beetle Brontispa longissima has been causing serious damage to the coconut palm Cocos nucifera in the Pacific, and Southeast and East Asia. This beetle also attacks Satakentia liukiuensis, an endemic palm on Ishigaki and Iriomote Islands, Japan. To assess the potential impact of B.longissima on S.liukiuensis, we examined the development period, survival rate, egg production and body size of B.longissima on S.liukiuensis at 22-31°C and consumption of S.liukiuensis leaf at 28°C. We also examined these life history traits on C.nucifera at 28°C to compare with those on S.liukiuensis. Brontispa longissima completed their development and reproduced on S.liukiuensis at 22-30°C. Linear regression analysis was used to estimate the effective cumulative temperature (k) as 891.2 degree-days, and the lower developmental threshold as 13.3°C. On the basis of these values and monthly average temperatures on Ishigaki Island, it was estimated that B.longissima has four generations per year on the island. Satakentia liukiuensis was less suitable for B.longissima than C.nucifera in terms of immature survival, development time, resultant adult size and reproduction. The low quality of S.liukiuensis as a host-plant may prevent the outbreak of B.longissima, which has not occurred yet on Ishigaki and Iriomote Islands. © 2012 The Entomological Society of Japan.

Thein M.M.,Khon Kaen University | Jamjanya T.,Khon Kaen University | Kobori Y.,Tropical Agriculture Research Front | Hanboonsong Y.,Khon Kaen University
Applied Entomology and Zoology | Year: 2012

Sugarcane white leaf disease is a serious problem in many Asian Countries. The leafhoppers Matsumuratettix hiroglyphicus (Matsumura) and Yamatotettix flavovittatus Matsumura are the main vectors of sugarcane white leaf disease phytoplasma. Gaining a better understanding of the dispersal behavior of such insect vectors is essential for both disease epidemiology and vector control. The dispersal distances of M. hiroglyphicus and Y. flavovittatus in a sugarcane field were estimated by means of mark-release-recapture experiments. Adult leafhopper vectors collected from the fields were marked using fluorescent dye powder and released at a central release point in a sugarcane field. The marking method did not have a significant effect on the survival or flight activity of the leafhopper vectors. The overall release-recapture rates of M. hiroglyphicus and Y. flavovittatus within 50 m were 10. 1 and 13. 4 %, respectively. The estimated natural mean dispersal distances for M. hiroglyphicus and Y. flavovittatus were 162. 1 and 387. 5 m, respectively. Wind appears to be the main factor influencing the leafhopper dispersal direction. © 2012 The Japanese Society of Applied Entomology and Zoology.

PubMed | Tokyo University of Agriculture, Tropical Agriculture Research Front and Nagoya University
Type: Journal Article | Journal: Biochemical and biophysical research communications | Year: 2015

Acetylcholine (ACh), a known neurotransmitter in animals and acetylcholinesterase (AChE) exists widely in plants, although its role in plant signal transduction is unclear. We previously reported AChE in Zea mays L. might be related to gravitropism based on pharmacological study using an AChE inhibitor. Here we clearly demonstrate plant AChE play an important role as a positive regulator in the gravity response of plants based on a genetic study. First, the gene encoding a second component of the ACh-mediated signal transduction system, AChE was cloned from rice, Oryza sativa L. ssp. Japonica cv. Nipponbare. The rice AChE shared high homology with maize, siratro and Salicornia AChEs. Similar to animal and other plant AChEs, the rice AChE hydrolyzed acetylthiocholine and propionylthiocholine, but not butyrylthiocholine. Thus, the rice AChE might be characterized as an AChE (E.C. Similar to maize and siratro AChEs, the rice AChE exhibited low sensitivity to the AChE inhibitor, neostigmine bromide, compared with the electric eel AChE. Next, the functionality of rice AChE was proved by overexpression in rice plants. The rice AChE was localized in extracellular spaces of rice plants. Further, the rice AChE mRNA and its activity were mainly detected during early developmental stages (2 d-10 d after sowing). Finally, by comparing AChE up-regulated plants with wild-type, we found that AChE overexpression causes an enhanced gravitropic response. This result clearly suggests that the function of the rice AChE relate to positive regulation of gravitropic response in rice seedlings.

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